This invention relates to a current conveyor circuit for accepting a current at an input at a low impedance and providing an output current of the same or a related value at an output at a high impedance comprising, a first transistor whose main current conducting path is connected between the input and a second diode connected transistor whose other end is connected to a voltage supply, a third transistor whose main current carrying path is connected between the voltage supply and a fourth diode connected transistor whose other end is connected to an input terminal for the application of a reference potential, and a fifth transistor whose control electrode is connected to the control electrodes of the second and third transistors and whose main current conducting path is connected between the supply voltage and the output, wherein the control electrodes of the first and fourth transistors are commoned.
A current conveyor circuit as set forth in the preceding paragraph is described in U.S. Pat. No. 3,582,689 and is generally known as a first generation current conveyor circuit or CC1. This circuit has the disadvantage that the input to which the reference voltage is applied takes the same current as the input current and consequently it is difficult to hold the reference voltage constant and hence the input impedance at the current input may rise. A second generation current conveyor circuit or CC2 is known but is generally formed using operational amplifiers. This adds complexity to the circuit and may require high supply voltages.